The invention relates to an automatic document feeder (ADF), and more particularly to an automatic document feeder that combines with office machines such as copy machines, scanners and fax machines to provide single-sided and double-sided image scanning.
The automatic document feeder is a machine that can combine with a copy machine, scanner, fax machine and the like, and can continuously process copying, scanning or facsimile on double-sided document paper. It does not require manual work. Consequently, efficiency is increased.
The automatic document feeder can be classified into two kinds, one is the single-sided scanning feeder, and the other is the double-sided scanning feeder. Regardless of whether the double-sided scanning feeder is used with a copy machine or a scanner, it can be divided into three types of feeders as follows:
(1) Double-sided copying or scanning attained by using two sets of optical structures. An optical structure is disposed above and below the delivery route established in the automatic document feeder. The upper and lower optical structures can simultaneously process image capture of a manuscript so as to do double-sided copying or scanning on the manuscript.
(2) Two sets of stepping motors and deceleration gears are disposed on the automatic document feeder. It is mainly furnished with two sets of power; one is used to provide delivery power for the manuscript, and the other is to provide power to a transmission mechanism to turn the manuscript upside down.
(3) The forward and reverse rotations of a motor are used to achieve double-sided copying or scanning. First, a manuscript is delivered to do the front side copying or scanning through the forward rotation of the motor, then rollers are used to keep the manuscript at its tail part. The motor is switched to reverse rotation at that time to enable the paper to rotate back, and be delivered through another route to be turned over on the return trip so as to attain the double-sided copying and scanning.
Although the three devises mentioned above can provide double-sided copying or scanning, due to the fact that two optical structure sets or two driving devices are installed on the automatic document feeder, it is large in volume, high in manufacturing expenses and difficult to manufacture. Besides, the device, which drives the manuscript to process double-sided copying and scanning through forward and reverse rotations, has a complex motor driving circuit design, and the motor life is relatively short.
The objective of the invention is to provide an automatic document feeder capable of processing double-sided copying or scanning through only the single rotation of a motor and only one set of optical mechanisms and driving devices.
Accordingly, the invention provides an automatic document feeder. A delivery route that can feed a manuscript through a scanning area, a return route and guiding-out route respectively connected with the delivery route are disposed in the automatic document feeder. A feeding mechanism used to drive the manuscript to move in the routes is installed around every route, and a guiding element and first and second guiding plates are installed at the intersection of the routes. Thereby, the manuscript can come out of the exit to complete single-sided scanning after passing through the scanning area. Then, the manuscript can be guided into the return route by the guiding element and turned over to the other side, and guided back to the delivery route to pass through the scanning area again to process the second scanning. Finally, the manuscript is guided out of the exit and the process of the double-sided image capture is completed.